Soil contamination can be caused by a variety of things, including for example, the presence of non-naturally occurring substances in the natural soil environment. The contamination can be caused by, for example, leakage from underground storage tanks, usage of pesticides, percolation of contaminated surface water to subsurface strata, oil and fuel dumping, leaching of wastes from landfills and/or direct discharge of industrial wastes to the soil. Some common substances found to contaminate soil include petroleum hydrocarbons, solvents, pesticides, lead and other heavy metals. Soil contamination presents health risks from the contact with the contaminated soil and contaminant vapors and from contamination of water supplies within the soil. Soil contamination can also have detrimental effects on ecosystems and agricultural lands.